Swift 6 Compatibility (#12)

# Fix Swift Concurrency

## ♻️ Current situation & Problem
Updates the flag name.


## ⚙️ Release Notes 
* Update swift concurrency flag name.


## 📝 Code of Conduct & Contributing Guidelines 

By submitting creating this pull request, you agree to follow our [Code
of
Conduct](https://github.com/StanfordSpezi/.github/blob/main/CODE_OF_CONDUCT.md)
and [Contributing
Guidelines](https://github.com/StanfordSpezi/.github/blob/main/CONTRIBUTING.md):
- [x] I agree to follow the [Code of
Conduct](https://github.com/StanfordSpezi/.github/blob/main/CODE_OF_CONDUCT.md)
and [Contributing
Guidelines](https://github.com/StanfordSpezi/.github/blob/main/CONTRIBUTING.md).

.github/workflows/build-and-test.yml

@@ -23,6 +23,17 @@ jobs:
       runsonlabels: '["macOS", "self-hosted"]'
       scheme: SpeziFoundation
       artifactname: SpeziFoundation.xcresult
+      resultBundle: SpeziFoundation.xcresult
+  packageios_latest:
+    name: Build and Test Swift Package iOS Latest
+    uses: StanfordSpezi/.github/.github/workflows/xcodebuild-or-fastlane.yml@v2
+    with:
+      runsonlabels: '["macOS", "self-hosted"]'
+      scheme: SpeziFoundation
+      xcodeversion: latest
+      swiftVersion: 6
+      artifactname: SpeziFoundation-Latest.xcresult
+      resultBundle: SpeziFoundation-Latest.xcresult
   packagewatchos:
     name: Build and Test Swift Package watchOS
     uses: StanfordSpezi/.github/.github/workflows/xcodebuild-or-fastlane.yml@v2

Package.swift

@@ -13,9 +13,9 @@ import PackageDescription
 
 
 #if swift(<6)
-let swiftConcurrency: SwiftSetting = .enableExperimentalFeature("SwiftConcurrency")
+let swiftConcurrency: SwiftSetting = .enableExperimentalFeature("StrictConcurrency")
 #else
-let swiftConcurrency: SwiftSetting = .enableUpcomingFeature("SwiftConcurrency")
+let swiftConcurrency: SwiftSetting = .enableUpcomingFeature("StrictConcurrency")
 #endif
 
 

Sources/SpeziFoundation/Misc/TimeoutError.swift

@@ -97,7 +97,8 @@ extension TimeoutError: LocalizedError {
 /// - Parameters:
 ///   - timeout: The duration of the timeout.
 ///   - action: The action to run once the timeout passed.
-public func withTimeout(of timeout: Duration, perform action: () async -> Void) async {
+@inlinable
+public func withTimeout(of timeout: Duration, perform action: @Sendable () async -> Void) async {
     try? await Task.sleep(for: timeout)
     guard !Task.isCancelled else {
         return

Sources/SpeziFoundation/Semaphore/AsyncSemaphore.swift

@@ -50,7 +50,7 @@ import Foundation
 /// ```
 ///
 /// - Warning: `cancelAll` will trigger a runtime error if it attempts to cancel tasks that are not cancellable.
-public final class AsyncSemaphore: @unchecked Sendable {
+public final class AsyncSemaphore: Sendable {
     private enum Suspension {
         case cancelable(UnsafeContinuation<Void, Error>)
         case regular(UnsafeContinuation<Void, Never>)
@@ -72,9 +72,9 @@ public final class AsyncSemaphore: @unchecked Sendable {
     }
 
 
-    private var value: Int
-    private var suspendedTasks: [SuspendedTask] = []
-    private let nsLock = NSLock()
+    private nonisolated(unsafe) var value: Int
+    private nonisolated(unsafe) var suspendedTasks: [SuspendedTask] = []
+    private let nsLock = NSLock() // protects both of the non-isolated unsafe properties above
 
 
     /// Initializes a new semaphore with a given concurrency limit.
@@ -90,17 +90,17 @@ public final class AsyncSemaphore: @unchecked Sendable {
     ///
     /// Use this method when access to a resource should be awaited without the possibility of cancellation.
     public func wait() async {
-        lock()
+        unsafeLock() // this is okay, as the continuation body actually runs sync, so we do no have async code within critical region
 
         value -= 1
         if value >= 0 {
-            unlock()
+            unsafeUnlock()
             return
         }
 
         await withUnsafeContinuation { continuation in
             suspendedTasks.append(SuspendedTask(id: UUID(), suspension: .regular(continuation)))
-            unlock()
+            nsLock.unlock()
         }
     }
 
@@ -112,19 +112,19 @@ public final class AsyncSemaphore: @unchecked Sendable {
     public func waitCheckingCancellation() async throws {
         try Task.checkCancellation() // check if we are already cancelled
 
-        lock()
+        unsafeLock() // this is okay, as the continuation body actually runs sync, so we do no have async code within critical region
 
         do {
             // check if we got cancelled while acquiring the lock
             try Task.checkCancellation()
         } catch {
-            unlock()
+            unsafeUnlock()
             throw error
         }
 
         value -= 1 // decrease the value
         if value >= 0 {
-            unlock()
+            unsafeUnlock()
             return
         }
 
@@ -134,28 +134,27 @@ public final class AsyncSemaphore: @unchecked Sendable {
             try await withUnsafeThrowingContinuation { (continuation: UnsafeContinuation<Void, Error>) in
                 if Task.isCancelled {
                     value += 1 // restore the value
-                    unlock()
+                    unsafeUnlock()
 
                     continuation.resume(throwing: CancellationError())
                 } else {
                     suspendedTasks.append(SuspendedTask(id: id, suspension: .cancelable(continuation)))
-                    unlock()
+                    unsafeUnlock()
                 }
             }
         } onCancel: {
-            self.lock()
-
-            value += 1
-
-            guard let index = suspendedTasks.firstIndex(where: { $0.id == id }) else {
-                preconditionFailure("Inconsistent internal state reached")
+            let task = nsLock.withLock {
+                value += 1
+
+                guard let index = suspendedTasks.firstIndex(where: { $0.id == id }) else {
+                    preconditionFailure("Inconsistent internal state reached")
+                }
+
+                let task = suspendedTasks[index]
+                suspendedTasks.remove(at: index)
+                return task
             }
 
-            let task = suspendedTasks[index]
-            suspendedTasks.remove(at: index)
-
-            unlock()
-
             switch task.suspension {
             case .regular:
                 preconditionFailure("Tried to cancel a task that was not cancellable!")
@@ -173,18 +172,20 @@ public final class AsyncSemaphore: @unchecked Sendable {
     /// - Returns: `true` if a task was resumed, `false` otherwise.
     @discardableResult
     public func signal() -> Bool {
-        lock()
+        let first: SuspendedTask? = nsLock.withLock {
+            value += 1
+
+            guard let first = suspendedTasks.first else {
+                return nil
+            }
 
-        value += 1
+            suspendedTasks.removeFirst()
+            return first
+        }
 
-        guard let first = suspendedTasks.first else {
-            unlock()
+        guard let first else {
             return false
         }
-
-        suspendedTasks.removeFirst()
-        unlock()
-
         first.suspension.resume()
         return true
     }
@@ -193,14 +194,13 @@ public final class AsyncSemaphore: @unchecked Sendable {
     ///
     /// This method resumes all `Task`s that are currently waiting for access.
     public func signalAll() {
-        lock()
-
-        value += suspendedTasks.count
+        let tasks = nsLock.withLock {
+            value += suspendedTasks.count
 
-        let tasks = suspendedTasks
-        self.suspendedTasks.removeAll()
-
-        unlock()
+            let tasks = suspendedTasks
+            self.suspendedTasks.removeAll()
+            return tasks
+        }
 
         for task in tasks {
             task.suspension.resume()
@@ -213,14 +213,13 @@ public final class AsyncSemaphore: @unchecked Sendable {
     ///
     /// - Warning: Will trigger a runtime error if it attempts to cancel `Task`s that are not cancellable.
     public func cancelAll() {
-        lock()
-
-        value += suspendedTasks.count
+        let tasks = nsLock.withLock {
+            value += suspendedTasks.count
 
-        let tasks = suspendedTasks
-        self.suspendedTasks.removeAll()
-
-        unlock()
+            let tasks = suspendedTasks
+            self.suspendedTasks.removeAll()
+            return tasks
+        }
 
         for task in tasks {
             switch task.suspension {
@@ -232,11 +231,11 @@ public final class AsyncSemaphore: @unchecked Sendable {
         }
     }
 
-    private func lock() {
+    private func unsafeLock() { // silences a warning, just make sure that you don't have an await in between lock/unlock!
         nsLock.lock()
     }
 
-    private func unlock() {
+    private func unsafeUnlock() {
         nsLock.unlock()
     }
 }

Tests/SpeziFoundationTests/SharedRepositoryTests.swift

@@ -33,10 +33,13 @@ private protocol AnyTestInstance {
 
     func testKeyLikeKnowledgeSource()
 
+    @MainActor
     func testComputedKnowledgeSourceComputedOnlyPolicy()
 
+    @MainActor
     func testComputedKnowledgeSourceComputedOnlyPolicyReadOnly()
 
+    @MainActor
     func testComputedKnowledgeSourceStorePolicy()
 }
 
@@ -66,8 +69,8 @@ final class SharedRepositoryTests: XCTestCase {
     }
 
     struct DefaultedTestStruct: DefaultProvidingKnowledgeSource, TestTypes {
-        var value: Int
         static let defaultValue = DefaultedTestStruct(value: 0)
+        var value: Int
     }
 
     struct ComputedTestStruct<Policy: ComputedKnowledgeSourceStoragePolicy>: ComputedKnowledgeSource {
@@ -76,7 +79,9 @@ final class SharedRepositoryTests: XCTestCase {
         typealias StoragePolicy = Policy
 
         static func compute<Repository: SharedRepository<Anchor>>(from repository: Repository) -> Int {
-            computedValue
+            MainActor.assumeIsolated {
+                computedValue
+            }
         }
     }
 
@@ -86,7 +91,9 @@ final class SharedRepositoryTests: XCTestCase {
         typealias StoragePolicy = Policy
 
         static func compute<Repository: SharedRepository<Anchor>>(from repository: Repository) -> Int? {
-            optionalComputedValue
+            MainActor.assumeIsolated {
+                optionalComputedValue
+            }
         }
     }
 
@@ -254,11 +261,12 @@ final class SharedRepositoryTests: XCTestCase {
         }
     }
 
-    static var computedValue: Int = 3
-    static var optionalComputedValue: Int?
+    @MainActor static var computedValue: Int = 3
+    @MainActor static var optionalComputedValue: Int?
 
     private var repos: [AnyTestInstance] = []
 
+    @MainActor
     override func setUp() {
         repos = [TestInstance(HeapRepository<TestAnchor>()), TestInstance(ValueRepository<TestAnchor>())]
         Self.computedValue = 3
@@ -314,14 +322,17 @@ final class SharedRepositoryTests: XCTestCase {
         repos.forEach { $0.testKeyLikeKnowledgeSource() }
     }
 
+    @MainActor
     func testComputedKnowledgeSourceComputedOnlyPolicy() {
         repos.forEach { $0.testComputedKnowledgeSourceComputedOnlyPolicy() }
     }
 
+    @MainActor
     func testComputedKnowledgeSourceComputedOnlyPolicyReadOnly() {
         repos.forEach { $0.testComputedKnowledgeSourceComputedOnlyPolicyReadOnly() }
     }
 
+    @MainActor
     func testComputedKnowledgeSourceStorePolicy() {
         repos.forEach { $0.testComputedKnowledgeSourceStorePolicy() }
     }

Tests/SpeziFoundationTests/TimeoutTests.swift

@@ -14,6 +14,7 @@ import XCTest
 final class TimeoutTests: XCTestCase {
     @MainActor private var continuation: CheckedContinuation<Void, any Error>?
 
+    @MainActor
     func operation(for duration: Duration) {
         Task { @MainActor in
             try? await Task.sleep(for: duration)
@@ -40,6 +41,7 @@ final class TimeoutTests: XCTestCase {
         }
     }
 
+    @MainActor
     func testTimeout() async throws {
         let negativeExpectation = XCTestExpectation()
         negativeExpectation.isInverted = true